Issue

Is clean build alive and well?

Clean Construction Protocol should be a critical consideration during high-tech facility design and construction. Here’s how it can be implemented into today’s construction techniques.

By Don Wadkins, Engineering Project Consultant

Ten years ago there was hardly an issue of CleanRooms or other technical journals related to high-tech construction that didn’t have some mention of clean builds. Not so now. Does that mean this is a thing of the past, a phase that has blown past us? Is Clean Construction Protocol (CCP) something that will be categorized like the buggy whip?

Not so. It is true that we don’t hear about it so often, but that is mostly because in the United States, at least, the construction of new semiconductor wafer fabs has leveled off dramatically. That is where CCP was used most frequently. However, this practice continues to be used in most projects where it is needed. This includes numerous nanoscience centers, both federal government funded at places such as Oak Ridge National Laboratory and Argonne National Laboratory, and at new research centers at both Sandia Labs and Los Alamos. Additionally, several universities have recognized that CCP is required for their nanoscience facilities that have been or are currently being constructed. Add to these projects other new cleanrooms at universities, which are not specifically dedicated to nanoscience projects and you get many more. This author is aware of projects at UCLA, the University of Houston, and the University of Louisville, and there are numerous others as well.

Click here to enlarge image

Though the building of new cleanrooms for equipment manufacturers that support microelectronics has diminished, where they have been added or modified some form of CCP has normally been used. The major implementations of clean build techniques are not visible in the United States because it hasn’t been happening here. It has been utilized extensively in offshore industrial facilities, especially in some very large wafer fabs that are providing foundry services to the world. Their dedication to clean build techniques has generally been more rigorous than here in our own country.

Who provides services?

If CCP is alive and well, where do you go to get advice about implementing it in your cleanroom project? All of the major engineering and construction firms that have experience with the design and construction of major cleanroom projects have this expertise. Even though their approaches and guide spec they use to begin determining an appropriate protocol varies a little, it is surprising how similar the processes are. That’s because over the years, they have all learned the hard lessons of what works and what does not. Not to pick on architects, because I have lots of friends in that profession, but many of the architectural firms do not have this expertise. They frequently rely on laboratory design consultants, who also generally do not have in-house expertise but generally know where to get it.

One place to look for help in the performance of CCP, not so much in the planning of it, is from janitorial firms. That’s because when a construction project actually gets under way, it is frequently the janitorial subcontractor who ensures that many of the conditions are satisfied. The management of these firms has seen an opportunity to provide these services, and provided an appropriate protocol that fits the project is established up front, they perform these services very well. There are a few exceptions, described later. For major manufacturing companies, especially in the semiconductor industry, where multiple cleanroom projects have transpired, there is normally an in-house expertise. These experts know what their requirements are, they are experienced in construction, and they write the specs. Even in this case, however, they most commonly rely on subcontractors to perform the hands-on activities and frequently the critical training as well.

Finally, there still exists a body of professionals operating as freelance consultants. Some of these professionals have previously worked on major projects, and, with the slowdown of building in microelectronics, have taken up work as consultants. Unfortunately, there hasn’t been enough work to keep all of them busy; some have retired, and it is a bit of a challenge to find them. For instance, the largest independent professional provider of these services during the boom years has now completely gone out of business.

Special case for high-purity piping

The installation of high-purity piping, for both gases and liquids, requires special attention. That is because the normal restrictions controlling airborne contamination, when used alone, are not effective in ensuring the success of piping for contamination-free fluids. Although most piping subcontractors are well versed on how to install systems in electropolished stainless steel, PVDF, and copper cleaned for oxygen service, these techniques are frequently beyond the understanding of general contractors and construction managers. Consequently, it is money well spent to have a third-party, high-purity piping quality control presence who provides testing services to validate the purity.

Certifying the cleanroom

The other specialty contractor, the one who finally wraps up the cleanroom project, is the certifier. This must be a well qualified professional agency, staffed by personnel who not only understand the delicate testing equipment they use but who are also experienced with common frailties of construction. It is also better if this agency is a third-party contractor, reporting to the owner rather than to the general contractor, to assure that all the “skeletons in the closet” are handled appropriately. The function of the certifier is to provide confidence. In this regard, his report should be a welcome one to the design company, verifying the correct facility design; to the general contractor and all the subcontractors, indicating that the construction was performed correctly; and to the owner, validating that he got what he paid for.

In order to discover and correct leaks in the cleanroom air filtration system, the certifier must always challenge the filters. This means a high concentration of particles must be introduced on the upstream side of the filters in order to reliably find and repair leaks-and there will always be leaks. As CCP has matured, the choice of challenge material has improved dramatically. At one time, there were those who advocated an ambient challenge, meaning the air upstream of the filters was dirty enough, and it needs to be several million particles per cubic foot, to satisfy this need. But this is hardly the case in a clean build project any more. The traditional challenge material was dioctyl phthalate (DOP). This very fine aerosol mist works very well. However, it carries with it a serious risk, because it will continue to outgas for years. Consequently, it is seldom used in microelectronic facilities and should never be used where optically sensitive surfaces will be used in the cleanroom. The material of choice for challenging filters is now polystyrene latex (PSL). This is also an aerosol, composed of tiny plastic spheres, the same material that is used to calibrate particle counters. It does not present the outgassing risk of DOP.

In addition to performing critical testing on the cleanroom filters and all mechanical systems, the certifier can frequently provide some unexpected bonuses. This is especially welcome because it comes at the tail end of the project, when schedule and cost pressures are always a factor. That is because professional certifiers go from one cleanroom project to another, and they have seen all of the problems occur that are imaginable. And they know what the last person did to fix them. Furthermore, they have an incentive to make your cleanroom a success, because their job isn’t done until it is considered successful. So the certifier is frequently your best friend in helping you past that last hurdle, a consultant when you had not expected one.

Cost/benefit of CCP

For CCP the bottom line is the bottom line. What does all this effort buy me? The single purpose of CCP is to give the owner confidence-confidence that the cleanroom will perform as it is intended to perform and fulfillment of the expectation that it will start up quickly, enabling the owner to begin to gain payback on this investment. And an assurance that there isn’t some horrible surprise hidden in the woodwork somewhere that will come back to bite you in the future. With a proper clean build project, you know there’s nothing in the woodwork, because you checked it all as you were putting it together!

That’s the benefit. But of course, there is the cost. These costs, when managed properly, are minimal compared to the overall project. Typically, the direct costs run less than one percent of the project. And even though it may include an enormous quantity of gloves, booties, and tacky mats for the duration, these commodities are really the lesser part of the cost. Most of it is in labor. There is the obvious labor of constant janitorial services. And there is the labor of a CCP manager, a professional who knows how to deal with contamination control issues and who understands construction. There are also some myths associated with the cost of building clean. One is that it has a dramatic impact on productivity. While putting on hairnets and gloves and wiping down tools and materials really does take a little time, it seldom adds more than five percent to the length of tasks. And although I’ve never figured out how to prove it, I am convinced that a clean build project typically has higher productivity than a conventional one. That is because the construction manager is forced to plan his activities much better than he ordinarily would. After all, planning is the main component of CCP.

Clean construction is like many other endeavors in one respect: You normally get what you pay for. Perhaps an anecdote is illustrative. The author was somewhat accidentally involved in solving a problem recently at a major nanoscience project. The project was well underway, a joint venture with a well respected engineering firm and an equally respected construction firm. The protocol spec was a good one, well suited to the project. During a visit to the site, the construction superintendent, who had not personally been involved in a clean build project before, confided that he didn’t think the cleanroom portion of the job, which had just begun, was going the way it should. This became apparent when I participated in the mandatory CCP training before being allowed to tour the project. The trainer who led in this session was very adamant about all the things that you couldn’t do. Everything was negative. There was no sharing of why the restrictions were needed. That’s because the instructor, the designated CCP manager, didn’t know why. Right up front it was apparent that she even misidentified the phase of construction that the project was in. She didn’t know what a particle counter was. It didn’t take long to find out how this problem had occurred. To begin with, the cleanroom subcontractor had been given the task of managing the CCP. That’s a mistake in itself, on the order of the fox in the henhouse. To initiate the protocol, this subcontractor had gone down to the labor union hall and hired the first body he could find and made this very energetic but totally unqualified person the CCP manager. Fortunately, it did not take long for corrective measures to be taken. But the project had been in jeopardy of becoming a very embarrassing, expensive failure.

Top 10 lessons learned

A ranking of lessons learned will vary among those who learned the lessons. But if all professionals who have managed clean build projects over the years were to compile separate top 20 lists, most certainly these 10 would be included in all of them.

1. Make sure the protocol is appropriate to the project. Jerry Greiner published his book, Cleanrooms, the Protocol, in 1993. He listed 10 commandments for developing a good CCP. These rules are still appropriate. Cleanrooms are designed to perform all sorts of functions, from painting automobiles, to filling pharmaceuticals, to fabricating integrated circuits, to performing open-heart surgery. The requirements for each of these are different, and the protocol appropriate for fabricating a facility to fulfill these diverse requirements must be custom-fitted to the goal of the cleanroom. One size does not fit all, and planning the rules to be enforced and the sequence of construction must be done with the objective in mind.

2. Make sure the CCP spec is in all the bid packages. The preparation for clean build must begin early enough that the requirements are made known to all prospective contractors, subcontractors, and material suppliers. The bid process should also identify contractors who are qualified to perform clean build work. If this is done, there will be very little, if any, increase in cost to the project above a conventional approach. Bidders will all compete to show their capabilities and will acknowledge the necessity of CCP. Failure to include the CCP spec, or an addition of it later, will always result in the proverbial claims for added cost due to productivity losses.

3. Design specs must provide for CCP. The CCP spec is just one of many that must ensure that the goals of the cleanroom can be met. The entire package of construction specs must recognize the ultimate goals and must be configured so that a protocol can be administered. There must be access to cleaning where necessary. Techniques and methods of construction must complement the CCP requirements. Another sad story is a recent project where the CCP program was a good one, but the piping specs were a disaster. Not only were they unclear about which spec applied, they also had a specific requirement for cleaned-for-oxygen service copper, designated for clean dry air, to be joined by soldering, rather than brazing. This technique would have ensured a never-ending source of contamination to this critical clean service. The piping contractor recognized this error and bid low to get the job; then he came back with continuous change orders to do the job right.

4. Optimize the work sequence. The most critical part of a CCP is to plan the work in the right sequence. Do the dirty work first, the clean work last, and never the twain shall meet. But of course, they have to meet sometimes, and when that happens ensure that protective measures are carefully incorporated and tested. It is best not to do stick welding in a clean environment, but if it must be done, mitigate with exhausted enclosures or a smoke hog. If you find yourself coring concrete in a bunny suit, something is wrong!

5. Use particle counters to illustrate the invisible. Particle counters are invaluable tools to monitor how clean your build progress is. Furthermore, there exist a variety of handheld models that are easy to use and can download data directly to spreadsheets. But don’t keep the results secret. Prepare frequent graphs and distribute them widely so the entire workforce can see the effectiveness of CCP measures. It keeps management happy, too, to see progress as it is made. It is a wonderful tool to evaluate workarounds and those necessary deviations from established protocol. I had always known that orbital welding was a clean operation, but it took an experiment with a particle counter to assure me that brazing copper did not significantly generate contamination like soldering the same piping did.

6. Make sure temporary storage is an asset, not a liability. Staging of construction materials is frequently a problem. If not managed firmly, subcontractors will have their materials delivered on-site, then put them inside the building under construction, generally in the way of other construction activities. This creates a serious contamination risk, because the space where these materials are located cannot be properly cleaned, and when it comes time to actually use the materials, they are contamination sources themselves. Laydown areas must be planned. They cannot interfere with orderly construction. Temporary structures for material storage are common alternatives.

7. Right supplies at the right time. Ironically, the opposite problem frequently occurs with respect to the commodities needed to keep a clean build job moving. The booties, gloves, tacky mats, hairnets, etc., that are required are all too often in short supply. These are relatively inexpensive materials, and they take very little space for storage. There is simply no justification for Just-in-Time, or rather just not in time, for them. And beware of the purchasing manager who tries to save a dime on booties that will only fit pygmies. Sometimes the best approach is to turn the task of supplying these items over to a vendor and give this vendor a little shed to keep full.

8. Never sacrifice safety for protocol. Although no competent construction manager would intentionally put a workforce at risk for the cause of building clean, it can sneak into a project-like the contamination-sensitive individual who insists on putting booties on the feet of ladders to protect the nice new cleanroom floors from the black marks that come from the bottom of the ladder when it is dragged. Nonsense. The ladder is supposed to be difficult to drag. How would you like to climb a ladder wearing booties when the ladder is wearing booties? And this unwarranted preoccupation with contamination control goes beyond construction protocol sometimes. Several years ago, there was a report of an entire wafer fab burning down (not in the United States) because the owner refused to install fire sprinklers in the cleanroom. It is true that the water inside those pipes is dirty if it is permitted to leak. But not nearly as dirty as a smoke-filled facility after it has burned for hours.

Click here to enlarge image

9. Only professional training works. Planning is the most important aspect for protocol. But training comes next. And it is effective only if the same degree of professionalism is given to the workforce that is expected from it. A sure way to put construction workers to sleep is to tell them they have to participate in mandatory training, then turn on a video player in a dark room when they arrive. Several years ago, at a major clean build project at Lawrence Livermore Labs in California, thousands of workers were exposed to a training regimen that included a photograph provided by one of the PhDs on-site of what happened to some very expensive laser optics when a tiny fragment of a rubber glove was left on the surface during a high-energy laser blast. The repair cost was a quarter of a million dollars. Later in the project, when a worker was climbing out of a confined space in his full cleanroom garb, he remembered that photo and confessed that a small piece of his latex glove had broken away. The quality control team wiped the inside of the precision cleaned vessel completely and couldn’t find the tiny piece of rubber. Then as the ironworker was removing his high-topped shoe covers, he found the fragment on the bottom of his foot. He had stepped on it on his way out of the vessel. Later, this worker confessed that he thought he would be fired for the incident. Instead, he was given major recognition for his dedication and even got a cash award.

10. Cleanup is chaos! In past surveys of clean build projects, the number one problem has been the cleanup. It is more effective to be persistent at pleading with people to do their part than to penalize them for not doing it. One approach is to require each subcontractor to have ten percent of his personnel dedicated to cleanup. But it usually makes sense to bite the bullet and plan on a dedicated janitorial crew to ensure that the job is done correctly. Furthermore, it also makes sense to have special training for the cleaning crew to ensure that they actually have filters in those HEPA vacs they use!

Don Wadkins started working in cleanrooms in 1969, then began designing and building them in 1988. He is mostly retired now but still works part-time for Jacobs Engineering in its Portland, OR, office and does some consulting relative to cleanrooms and process chemicals. He has a B.A. in chemistry and an MBA in management, and is a former National Director for the Institute of Environmental Sciences.